PAN-POSS接枝共聚物改性聚环氧乙烷/离子液体凝胶电解质的制备及性能

Preparation and Properties of PAN-POSS Graft Copolymer Modified Polyethylene Oxide/Ionic Liquid Gel Electrolyte

采用自由基聚合法成功合成了聚丙烯腈与笼型倍半硅氧烷的接枝共聚物(PAN-POSS),并将其引入聚环氧乙烷(PEO)/1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐([EMIM][TFSI])/双三氟甲磺酰亚胺锂(LiTFSI)体系,通过溶剂挥发法制备具有自支撑性的凝胶电解质(GPEs)。采用差示扫描量热分析、热分析、拉伸测试和电化学性能测试等进行表征,研究了PAN-POSS含量对PEO基电解质结晶性能、力学性能、热稳定性和电化学性能的影响。结果表明,在PEO/[EMIM][TFSI]/LiTFSI凝胶电解质体系中,随PAN-POSS含量增加,PEO的结晶度逐渐降低,当质量分数为9%时,结晶度从初始的25.7%降至11.6%。此时,GPEs的室温离子电导率为2.87×10^(-4) S/cm,在0.1 C充电速率下,电池的容量达到130 mAh/g。PAN-POSS的添加提高了GPEs的热稳定性,热降解温度可达到380.6℃,力学性能略有下降,但是仍然达到3.3 MPa,具有良好的自支撑特性。

A graft copolymer of polyacrylonitrile and cage-type sesiloxane(PAN-POSS) was successfully synthesized by free radical polymerization. The self-supporting gel polymer electrolytes(GPEs) were prepared by introducing PAN-POSS into the system of poly(ethylene oxide)(PEO)/1-ethyl-3-methylimidazolium bis trifluoromethulfimide salt([EMIM][TFSI])/lithium bis trifluoromethulfimide(LiTFSI). GPEs were characterized by differential scanning calorimetry analysis, thermal analysis, tensile test and electrochemical test. The effect of PAN-POSS content on the crystallinity, mechanical properties, thermal stability and electrochemical properties of PEO-based electrolytes was studied. The results show that in PEO/[EMIM][TFSI]/LiTFSI gel electrolyte system, with the increase of PAN-POSS content, the crystallinity of PEO gradually decreases. When the mass fraction of PAN-POSS is 9%, the crystallinity from the initial 25.7% drops to 11.6%. The room temperature ionic conductivity of GPEs is 2.87×10^(-4) S/cm, and the battery capacity reaches 130 mAh/g at a charging rate of 0.1 C. The addition of PAN-POSS improves the thermal stability of GPEs, the thermal degradation temperature reaches 380.6 ℃, and the mechanical properties are decreased slightly, but the tensile strength still reaches 3.3 MPa.